Contacts for electric circuit breakers



April 2, 1957 R. E. HALL CONTACTS FOR ELECTRIC CIRCUIT BREAKERS FiledFeb. 6, 1956 INVENTOR RICHMOND E. HALL.

United States Patent 2,787,687 CONTACTS FOR ELECTRIC CIRCUIT BREAKERSRichmond Ernest Hall, Ilford, England, asslgnor to The Plessey CompanyLimited, llford, England, a British company Application February 6,1956, Serial No. 563,823

3 Claims. (Cl. 200-166) This invention relates to contacts for electriccircuit breakers.

The object of the invention is to provide a contact member in compactform possessing a high degree of resilience, which is also relativelycheap to produce.

The invention essentially consists of a moving contact member which isconstructed from a blade spring of which the opposed ends are eachfitted with electrical contacts and wherein the intermediate portion ofsaid spring is bent in a returning curve. The bending or folding of theintermediate portion of said spring increases the resiliency of thecontact-carrying ends, so that during the usual follow-through actionagainst the fixed contacts a wiping action will generally occur betweenthe contacting surfaces.

An electrical contact is fixed to the respective ends of the spring forengagement with similar fixed contacts. In the case of a two-way switch,contacts are fixed to both faces of the spring to engage with similarfixed contacts when moved in alternate directions from the neutral oropen position.

A feature of the invention is that the intermediate portion of thespring leaf is provided with means for rockably mounting the movingcontact member in a suitable carrier.

Thus from one aspect the invention consists in a balanced contactmember, comprising a blade spring having contacts at each end and beingbent to include an S bend between said contacts, whereby the resilienceof the blade spring is increased for a given distance between saidcontacts, said blade spring being formed with a pair of aligned integrallugs projecting laterally from the two edges of the blade springapproximately halfway between the two contacts. The leaf spring may belaminated, preferably with a number of thin sections to provideincreased resiliency.

The accompanying drawing illustrates one embodiment of this invention.Figure 1 is an exploded perspective view of a contact assembly for anelectrical relay or other circuit breaker having two contact members,one of which has been omitted to expose more details of thecontact-carrier structure, and

Figure 2 is a section through part of a contact member.

Referring now to the drawing, the contact member consists of a springblade of suitable metal having the intermediate portion folded toapproximately an 8- formation. The longitudinal edges of the centre limbof the folded section are formed with. projecting lugs 12. The two endsof the spring blade 10 co-planar and carry each a double contact element13, 14.

Where the circuit breaker is to be used for heavy currents and in orderto obtain a higher degree of resilience, the spring blade 10 carryingthe contact elements 13, 14 may consist of several thin laminations, asindicated at 10a, 10b, 10c and 10d in Figure 2. The latter figure alsoshows the manner in which the contact elements 13, 14 are secured to theblade 10.

In the contact assembly illustrated in Figure 1 a plurality of contactmembers 1 are rockably mounted by their attachment lugs 12 in elongatedapertures 15 of a con- 2,787,687 Patented Apr. 2, 1957 tact-holder barcomprising two identical bar elements 2. These elements are joined, withtheir corresponding faces 20 in contact, by spring rings or the like(not shown) engaging notches 21 at the back of each element 2 adjacenteach end theerof. Grooves 22 extend across the face 20 of each member 2and are so arranged and dimensioned that each pair of correspondinggrooves 22 forms a passage which when the two members 2 are assembledwith the contact members 1 in position, will accommodate the centreportion of the blade 10 and confine it against lateral movement whileallowing it to rock about the lugs 12. The apertures 15 are somewhatwider than the thickness of these lugs so as to allow a limited amountof such rocking movement. The construction may be adapted to a varietyof uses by mounting in a pair of bar members 2 of suitable length two ormore contact members 1, each being accommodated in a separate pair ofgrooves 12 and pivoted in apertures 15 as hereinabove described. Thecontact members 1 constitute the movable contacts, which will co-operatewith suitably mounted stationary contacts. In all cases equal contactpressures at the two sides can be maintained irrespective of minorinaccuracies in the location of the contacts, due to the rockablemounting of the members 1. Any conventional form of mechanical means maybe used for actuating the bar assembly to open and close the circuit orcircuits.

It will be evident from the foregoing description that the inventionprovides flexible contact member which when brought into engagement withfixed contacts provides a wiping action which in operation tends toclean the contact surface.

What is claimed is:

1. A balanced contact member, comprising a blade spring having contactsat each end and being bent to include an S bend between said contacts,whereby the resilience of the'blade spring is increased for a givendistance between said contacts, said blade spring being formed with apair of aligned integral lugs projecting laterally from the two edges ofthe blade spring approximately halfway between the two contacts.

2. A balanced contact member, comprising a blade spring having twocoplanar end portions, integrally connected by an intermediate portionbent to a substantially S-like shape about axes parallel to the plane ofsaid end portions and perpendicular to a line connecting said portions,and contact elements secured to each said end portion, the centre ofsaid S-like shape being perpendicular to the plane of said end portionsand provided at its two sides with aligned integral lugs.

3. A contact assembly for electrical relays and like contact devices,comprising a bar formed by a pair of complementary bar elements ofinsulating material having mutually facing transverse grooves jointlyforming passages across said bar and having apertures extending throughthe bar transversely to the bar elements and to the grooves, saidapertures intersecting the said passages and being elongated in thedirection of the bar, and balanced contact members, as claimed in claim2, each extending through one of said passages with its contact elementson the two end portions exposed outside the bar and with its lugs lodgedin said apertures, the dimensions beingsuch as to allow a limited amountof rocking movement of said lugs in said apertures to balance contactpressures.

References Cited in the file of this patent UNITED STATES PATENTS998,786 Loefiier July 25, 1911 2,529,652 Dicke Nov. 14, 1950 2,532,305Heller Dec. 5, 1950 2.626.334 Koenig Jan. 20, 1953

